A pulsation dampener is presented which includes a bladder assembly having a bladder which retains its surface area and therefore its capability to dampen pulsations during pulsation dampening. The bladder is axially and longitudinally symmetrical. The bladder assembly comprises a bladder double sealed...http://www.google.com/patents/US3893485?utm_source=gb-gplus-sharePatent US3893485 - Pulsation dampener

A pulsation dampener is presented which includes a bladder assembly having a bladder which retains its surface area and therefore its capability to dampen pulsations during pulsation dampening. The bladder is axially and longitudinally symmetrical. The bladder assembly comprises a bladder double sealed at both longitudinal ends by the combination of a bladder anchor bolt and a pressed metal end plate to prevent leakage. Pulsation causes the bladder to assume a clover leaf cross sectional configuration, thereby maintaining the bladder surface area constant regardless of pulsation. One end of the housing is machined so that that end may be pressed to gradually reduce its diameter toward the end while causing the wall thickness of those portions of diminishing diameter to remain essentially identical to the thickness of the unmachined unpressed wall portions of the housing.

BACKGROUND OF THE INVENTION 1. FIELD OF THE INVENTION The present invention relates to pulsation dampeners.

2. DESCRIPTION OF THE PRIOR ART The prior art discloses a variety of pulsation dampeners many of which utilize bladders. some of the prior art designs have relatively short bladder life, requiring relatively frequent replacement. Some of the prior art pulsation dampeners because of their shape, size, orientation or weight have less flexibility than is desirable. Many of the prior art bladders cannot be easily assembled and dissembled. Many require a central mandrel.

Most of the above described disadvantages are overcome by pulsation dampener described in US. Pat. No. 2,968,319 by Melvin A. Ball. The Ball pulsation dampener uses a bladder inside a metal screen having holes therethrough, the two being tightly affixed to the interior of a housing. The interior of the bladder has been filled with a gas such as nitrogen at a pressure of approximately 500 pounds per square inch. As fluid flows in an opening in the housing under pulsations from the external line, the fluid passes through perforation holes of the screen and presses against the bladder. The pressure of the fluid forces the bladder inward thereby compressing gas inside the bladder and dissipating the energy and pressure resulting from the pulsations of the fluid in the external line.

While the Ball pulsation dampener contains significant improvements over the prior art, it contains serious disadvantages as well. The bladder is not longitudinally symmetrical. Accordingly, the two opposite ends are unable to symmetrically or identically contract when subjected to pulsations from the external line. This causes a tendency for the bladder to wrinkle, thereby reducing the surface area of the bladder. Reduction of the surface area of the bladder reduces the capability of the pulsation dampener to dampen the pulsations. In addition, the wrinkling of the bladder during pulsations reduces the life of the bladder. The bladder design required by the Ball Patent is difficult to visually inspect internally prior to installation thereby causing many early bladder failures because of undetected faults. In addition, the design of the Ball pulsation dampener includes structures which have a great deal of weight thereby making the pulsation dampener excessively heavy and cumbersome as well as difficult to manufacture. In practice, the Ball pulsation dampeners have a tendency to leak, thereby gradually reducing their capability to dampen pulsation.

SUMMARY OF THE INVENTION A pulsation dampener is presented. A first example comprises a housing having a bladder assembly disposed around an axis attached therein. The bladder assembly comprises a generally cylindrical screen having a large quantity of small openings therethrough and further includes a pressurized flexible longitudinally and axially symmetrical generally cylindrical bladder therein One end of the housing, hereafter called the aft end includes a center guide plug which defines an interior surface fitting relatively tightly around the adjoining exterior surface of the bladder assembly.

The bladder assembly is placed inside the housing to assemble the pulsation dampener. The interior surface of the housing defines a circumferential groove around the interior circumference at approximately the top of the inserted bladder assembly. A four-piece locking ring assembly is fitted into the groove. The bladder assembly is then coupled to the locking ring assembly by three cap screws or similar coupling means. An allen set screw is then screwed through a threaded opening at the bottom of the housing and screwed against the aft end of the bladder assembly to hold it tightly against the locking ring assembly. A rubber plug is then inserted into the hole through which the allen set screw has been screwed tightly against the bladder assembly. A second allen set screw is then screwed in to squeeze the rubber plug against the aft end of the first allen set screw. thereby causing the rubber plug to form a tight seal.

The bladder assembly comprises an axially and longitudinally symmetrical bladder and supporting structure. A mushroom shaped bladder anchor is bolted to an anchor bolt and placed head in inside the aft end of the bladder. Each end of the bladder includes a thickened circular axially symmetrical lip which defines an opening. Each lip of the bladder then comes over the underside of the head of the anchor. A disc shaped metal end cap having an axial circular hole of the diam eter of the anchor bolt and shaped to mate with the under portion of the mushroom shaped head of the anchor is then placed over the anchor and covers the end of the bladder. The anchor bolt extends through the axial hole through the end cap and is bolted to a spacer nut, the exterior surface of which mates with the interior surface of the center guide plug.

The fore end of the bladder assembly utilizes an anchor and anchor bolt having an axial valve therethrough. This valve extends out of the housing to permit control in checking of the pressure within the bladder. The anchor bolt is placed through the axial hole in a second end cap and bolted to a cylindrical plug. The external circumference of the plug defines a circumferential groove in which an O ring is placed. When the bladder assembly is placed in the housing, the O ring forms a seal with the interior surface of the housing.

The disc-shaped end caps are welded convex side outward to the screen. The second welding with the bladder and other components inside should be done under water. The interior surface of each end cap is shaped to mate with the bottom of the adjacent anchor. There is metal to metal contact between the adjacent surfaces of the end cap and anchor and the lip is slightly squeezed between the end cap and anchor to form two seals, one against the anchor and one against the end cap.

The locking ring assembly comprises three parts which together form an annulus capable of fitting tightly in the groove around the interior circumference of the housing. The first two pieces of the assembly are identical and are inserted first, leaving a space which is filled by putting the third part near the axis and sliding it back against the housing. A locking ring keeper is inserted to hold the other pieces of the assembly against the housing. Each of the first three pieces contains a hole through which the assembly is bolted to the adjacent plug by cap screws. The cap screws overlap the central portion of the locking ring thereby securely holding the locking ring assembly.

The housing is fabricated from a cylindrical shell of wall thickness sufficient to stand the anticipated pressures. One end of the shell is machined to gradually reduce wall thickness as the end is approached. That end is then pressed to reduce the outer surface diameter as the end is approached. Pressing the end so as to reduce the outer diameter has a tendency to thicken the walls since the same amount of material then forms an annu lus of lesser outer diameter. The amount of material removed by machining is such that the pressing causes the wall strength to be constant at the end where the diameter of the cylinder is reduced and equal to the strength of the unmachined and unpressed wall portions of the cylinder.

The center guide plug interior surface is machined to mate with the aft end of the bladder assembly. A threaded allen set screw hole is tapped through it. The center guide plug is then coupled to the narrow end of the housing by means such as welding which form a strong permanent seal. Pressing the aft end of the housing through a narrower diameter makes it mate with the aft end of the bladder assembly.

The pulsation dampener according to the present invention has long shelf and use life. The aft end includes a permanent seal around the center guide plug and a very strong seal by means of the rubber plug between the two allen set screws. The fore end includes a strong seal by means of the O ring around the plug and the adjacent interior surface of the housing. The bladder is strongly double sealed at both ends by the anchor squeezing the lip of the bladder against the end cap. The interior surface of the end cap, the lip of the bladder and the surface of the anchor are designed to form strong seals. The valve extends out through the locking ring to permit easy checking and controlling of the pressure inside the bladder. An end plate may be used to cover the fore end of the housing.

The fact that the bladder is longitudinally and axially symmetrical is critical. Other structures and shapes described herein are examples only and may be replaced by various equivalents known to the prior art.

A cover plate is utilized to prevent damage to the loading valve.

DRAWING SUMMARY Reference should be made at this time to the following detailed description which should be read in conjunction with the following drawings:

FIG. I is a partially cut away side view of a bladder assembly according to the present invention;

FIG. 2 is a side view of a housing for the bladder assembly of FIG. 1',

FIG. 3 is a top view of a four-piece locking ring; and

FIG. 4 is a cross sectional view taken along the lines 4-4 of FIG. 1 of a selected portion of the bladder assembly of FIG. 1 during pulsation.

DETAILED DESCRIPTION Reference should be made at this time to FIGS. 1, 2 and 3 which illustrate a bladder assembly 12 disposed around an axis, and housing 22 ofa pulsation dampener 10. The bladder assembly 12 includes a generally cylindrical bladder 14 which is longitudinally and axially symmetrical, fabricated from a flexible strong material such as artificial rubber, and disposed around an axially symmetrical opening 24 at each end which opening 24 is approximately one-half the diameter of the bladder 14. The bladder 14 is contained within a generally cylindrical bladder screen 26 having a large quantity of bladder screen holes 28 therethrough. The opening 24 of the aft end of the bladder 14 has a bladder anchor I6 with a coaxial anchor bolt 30 threaded therein. The anchor 16 and bolt 30 are co-axial with the bladder 14 and the bladder screen 26. The anchor bolt 30 fits through an axially symmetrical hole 46 in an end cap 36 to bolt the anchor 16 to a spacer nut 32 which is axially symmetrical and also disposed along the common axis. The thickened circular lip 34 which is disposed around the bladder opening 24 is pressed to form a seal with the end cap 36 and a second seal with the anchor 16. The anchor I6 has a mushroom-like shape. The disc shaped end cap 36 has an interior center portion 40 which is pressed to fit tightly over the bottom 42 of the anchor 16 and the lip 34. The thickness of each lip 34 is slightly greater than the height of the lower portion of the adjacent anchor. There is metal to metal contact between each anchor and the adjacent end cap 36.

In order to fabricate the bladder assembly 12, the end cap 36 is pressed into the proper shape, then welded to the cylindrical portion 44 of the screen 26. The anchor I6 is bolted to the bolt 30 and placed inside the bladder 14. The anchor bolt 30 is oriented outside of the bladder 14 through the mating co-axial anchor bolt opening 46 through the end cap 36, and bolted to the spacer nut 32.

The fore end of the bladder assembly I2 is built up in a similar manner with the following changes. A fore anchor 48 and anchor bolt 51 have an axial valve therethrough to permit inflation of the bladder 14. The end cap 36 is welded to the cylindrical portion 44 of the screen 26 under water after the anchors I6, 48 have been inserted in the bladder 14 and the bladder 14 has been inserted into the cylindrical portion 44 of the screen 26. The anchor bolt 48 is then bolted to a cylindrical plug 52. The bladder assembly 12 is then inserted in the open end of the housing 22 so that the spacer nut 32 nests in and mates with the interior of a center guide plug 70.

A four-piece locking ring assembly 20 is then inserted as follows. A first locking ring segment is laid adjacent the plug 52 and inserted in the locking ring groove 74 which is a circumferential groove around the interior of the housing 22. The second locking ring segment 60 is then inserted in the locking ring groove 74 and slid so that one segment end 76 is adjacent the segment end 76 of the other segment 60. Accordingly. the second segment ends 78 are parallel and disposed apart the width of the locking ring filler 62. The locking ring filler 62 is laid between the second segment ends 78 near the axis of the bladder assembly 12 and slid away from the axis into the groove 74. A Circular locking ring keeper 58 is then inserted between the other three pieces 60, 62 of the locking ring assembly 20, thereby stabilizing the locking ring assembly 20. A threaded cap screw hole 84 through each of the two locking ring segments 60 and the locking ring filler 62 continues through the outer surface of the plug 52. The holes 84 are equidistant from each other and disposed around the axis 120 apart.

An interior allen set screw 64 is then screwed through the threaded allen set screw tapped hole to force the spacer nut 32 toward the locking ring assembly 20, thereby stabilizing the bladder assembly 12, and

preventing harmful vibrations when pulsations are received. A rubber plug 66 is then pushed up against the interior allen set screw 64 and squeezed tight forming a seal by the insertion of the outer allen set screw 68.

Reference should be made at this time to FIG. 4 which illustrates a cross section along the lines 4 of the bladder 14 during pulsations. Pulsations do not wrinkle the bladder 14, they merely cause it to assume a cloverleaf configuration wherein the total surface area remains essentially the same. Accordingly, since the surface area of the bladder 14 is not folded together or wrinkled during pulsations, the pulsation dampening capability of the pulsation dampener is not reduced and bladder life is extended.

The housing 22 is fabricated from a cylindrical shell of wall thickness sufficient to stand the anticipated pressure pulsations which act on the bladder assembly through a hole 82 in the housing wall. One end of the shell is machined to gradually reduce wall thickness as the end is approached. That end is then pressed to reduce the outer surface diameter as the end is approached. Pressing the end so as to reduce the outer diameter has a tendency to thicken the walls since the same amount of material then forms an annulus of lesser outer diameter. The amount of material removed by machining is such that the pressing causes the wall strength to be constant at the end where the diameter of the cylinder is reduced and equal to the strength of the unmachined and unpressed wall portions of the cylinder.

The center guide plug 70 interior surface is machined to mate with the aft end of the bladder assembly 12. A threaded allen set screw hole 80 is tapped through it. The center guide plug 70 is then coupled to the narrow end of the housing 22 by means such as welding which forms a strong permanent seal. Pressing the aft end of the housing 22 to a narrower diameter reduces weight and provides a closer fit around the aft end of the bladder assembly 12.

A pulsation dampener according to the present invention has long shelf and use life. The aft end includes a permanent seal around the center guide plug 70 and a rubber plug 66 between the two allen set screws 64, 68. The fore end includes a strong seal by means of the O ring 56 around the plug 52 and the adjacent interior surface of the housing 22. The bladder 14 is strongly double sealed at each end by the anchor 16, 48 squeezing the lip 34 of the bladder 14 against the end cap 36. The interior surface of the end cap 36, the lip 34 of the bladder 14 and the side of the adjacent anchor 16, 48 are designed to form a strong permanent seal. The adjacent wall of each end cap 36 and the wall 42 of each anchor 16, 48 form a metal to metal contact. The valve 50 extends out through the locking ring assembly to permit easy checking and controlling of the pressure inside the bladder 14. An end plate may be used to cover the fore end of the housing 22.

The fact that the bladder 14 is longitudinally and axially symmetrical is critical. Other structures and shapes described herein are examples only and may be replaced by various equivalents known to the prior art. A cover plate is utilized to prevent damage to the loading valve 50.

I claim:

1. A bladder assembly for a pulsation dampener comprising:

a flexible cylindrical bladder with generally dome shaped end walls each having an opening on the axis of the bladder and a thickened annular rim portion surrounding said opening and forming about the opening an inner axially projecting sealing lip at the inner side of the respective end wall and an outer axially projecting sealing lip at the outer side of the respective end wall,

two anchors each having a central portion extending through a respective bladder opening and an enlarged head portion seating against the inner side of the respective bladder end wall and containing an annular sealing groove receiving the respective inner sealing lip of the bladder,

two anchor bolts each coaxially secured to a respective anchor and extending externally of said bladder,

two generally dome shaped end caps each fitting over a respective end of said bladder and having an annular sealing shoulder surrounding and engaging the respective outer sealing lip of said bladder and a central opening through which the corresponding anchor bolt extends,

a generally cylindrical screen extending between the two end caps in surrounding relation to said bladder and joined to said end caps, and

one anchor bolt containing an axial passage through which the interior of said bladder may be pressurized.

2. The bladder assembly according to claim 1 wherein:

each anchor is generally mushroom shaped, and

a nut threaded on each anchor bolt for firmly clamping the respective anchor, bladder end wall and sealing lips and end cap together into sealing relamen.

3. A bladder assembly according to claim 2 in combination with:

a generally cylindrical housing containing said bladder assembly and having an end wall closing one end of the housing and an opposite open end, and an opening in said housing communicating to the interior of said housing about said bladder,

the nut threaded on said one anchor bolt comprising a disc shaped plug slidably fitting within and sealing said open housing end,

said housing end wall has an inner coaxial recess receiving the other nut, and

means releasably securing said plug in said housing.

4. The combination according to claim 3 including:

a screw threaded in said housing end wall and engaging said other nut for pressing said bladder assembly tightly against said plug.

5. The combination according to claim 3 wherein:

said housing end wall diminishes in thickness progressively toward said end wall recess.

6. The combination according to claim 3 wherein:

said plug securing means comprises a locking ring assembly including separate parts seating against the outer side of said plug and engaging within an internal annular groove in said open housing end, and means releasably retaining said parts in said groove.

7. A bladder assembly according to claim 1 wherein:

said bladder end wall openings have equal diameters and said anchors have the same size and shape.